Synthetic Quantum Systems

So far proposed quantum computers use fragile and environmentally sensitive natural quantum systems. Here we explore the new notion that synthetic quantum systems suitable for quantum computation may be fabricated from smart nanostructures using topological excitations of a stochastic neural-type network that can mimic natural quantum systems. These developments are a technological application of process physics which is an information theory of reality in which space and quantum phenomena are emergent, and so indicates the deep origins of quantum phenomena. Analogous complex stochastic dynamical systems have recently been proposed within neurobiology to deal with the emergent complexity of biosystems, particularly the biodynamics of higher brain function. The reasons for analogous discoveries in fundamental physics and neurobiology are discussed.Comment: 16 pages, Latex, 1 eps figure fil

Timelike self-similar spherically symmetric perfect-fluid models

Einstein's field equations for timelike self-similar spherically symmetric perfect-fluid models are investigated. The field equations are rewritten as a first-order system of autonomous differential equations. Dimensionless variables are chosen in such a way that the number of equations in the coupled system is reduced as far as possible and so that the reduced phase space becomes compact and regular. The system is subsequently analysed qualitatively using the theory of dynamical systems.Comment: 23 pages, 6 eps-figure

Do patients at risk of infective endocarditis need antibiotics before dental procedures?

What you need to know: - Patients with prosthetic heart valves, previous infective endocarditis, and some types of congenital heart disease are at highest risk of infective endocarditis - Invasive dental procedures cause bacteraemia, which can be complicated by infective endocarditis in those at increased risk of the disease - Antibiotic prophylaxis reduces the incidence of bacteraemia, but high level studies confirming that this reduces the incidence of infective endocarditis are lacking - Warn high risk patients undergoing high risk dental interventions of the risk of infective endocarditis. Offer these patients antibiotic prophylaxis, and discuss with them the risks and benefits of this option - Where patients are at moderate risk, encourage preventative measures, such as maintaining good oral hygiene and infection control, and discourage tattooing or piercin

Molecular Electroporation and the Transduction of Oligoarginines

Certain short polycations, such as TAT and polyarginine, rapidly pass through the plasma membranes of mammalian cells by an unknown mechanism called transduction as well as by endocytosis and macropinocytosis. These cell-penetrating peptides (CPPs) promise to be medically useful when fused to biologically active peptides. I offer a simple model in which one or more CPPs and the phosphatidylserines of the inner leaflet form a kind of capacitor with a voltage in excess of 180 mV, high enough to create a molecular electropore. The model is consistent with an empirical upper limit on the cargo peptide of 40--60 amino acids and with experimental data on how the transduction of a polyarginine-fluorophore into mouse C2C12 myoblasts depends on the number of arginines in the CPP and on the CPP concentration. The model makes three testable predictions.Comment: 15 pages, 5 figure

Incorporating Prior Knowledge on Class Probabilities into Local Similarity Measures for Intermodality Image Registration

We present a methodology for incorporating prior knowledge on class probabilities into the registration process. By using knowledge from the imaging modality, pre-segmentations, and/or probabilistic atlases, we construct vectors of class probabilities for each image voxel. By defining new image similarity measures for distribution-valued images, we show how the class probability images can be nonrigidly registered in a variational framework. An experiment on nonrigid registration of MR and CT full-body scans illustrates that the proposed technique outperforms standard mutual information (MI) and normalized mutual information (NMI) based registration techniques when measured in terms of target registration error (TRE) of manually labeled fiducials

Can a Logarithmically Running Coupling Mimic a String Tension?

It is shown that a Coulomb potential using a running coupling slightly modified from the perturbative form can produce an interquark potential that appears nearly linear over a large distance range. Recent high-statistics SU(2) lattice gauge theory data fit well to this potential without the need for a linear string-tension term. This calls into question the accuracy of string tension measurements which are based on the assumption of a constant coefficient for the Coulomb term. It also opens up the possibility of obtaining an effectively confining potential from gluon exchange alone.Comment: 13 pages, LaTeX, two figures not included, available from author. revision - Line lengths fixed so it will tex properl

Spatially self-similar spherically symmetric perfect-fluid models

Einstein's field equations for spatially self-similar spherically symmetric perfect-fluid models are investigated. The field equations are rewritten as a first-order system of autonomous differential equations. Dimensionless variables are chosen in such a way that the number of equations in the coupled system is reduced as far as possible and so that the reduced phase space becomes compact and regular. The system is subsequently analysed qualitatively with the theory of dynamical systems.Comment: 21 pages, 6 eps-figure

Separability of Two-Party Gaussian States

We investigate the separability properties of quantum two-party Gaussian states in the framework of the operator formalism for the density operator. Such states arise as natural generalizations of the entangled state originally introduced by Einstein, Podolsky, and Rosen. We present explicit forms of separable and nonseparable Gaussian states.Comment: Brief Report submitted to Physical Review A, 4 pages, 1 figur

The state space and physical interpretation of self-similar spherically symmetric perfect-fluid models

The purpose of this paper is to further investigate the solution space of self-similar spherically symmetric perfect-fluid models and gain deeper understanding of the physical aspects of these solutions. We achieve this by combining the state space description of the homothetic approach with the use of the physically interesting quantities arising in the comoving approach. We focus on three types of models. First, we consider models that are natural inhomogeneous generalizations of the Friedmann Universe; such models are asymptotically Friedmann in their past and evolve fluctuations in the energy density at later times. Second, we consider so-called quasi-static models. This class includes models that undergo self-similar gravitational collapse and is important for studying the formation of naked singularities. If naked singularities do form, they have profound implications for the predictability of general relativity as a theory. Third, we consider a new class of asymptotically Minkowski self-similar spacetimes, emphasizing that some of them are associated with the self-similar solutions associated with the critical behaviour observed in recent gravitational collapse calculations.Comment: 24 pages, 12 figure

Risk of neuropsychiatric and cardiovascular adverse events following treatment with varenicline and nicotine replacement therapy in the UK Clinical Practice Research Datalink:a case-crossover study

BACKGROUND AND AIMS: Varenicline and nicotine replacement therapy (NRT) are the most commonly used medications to quit smoking. Given their widespread use, monitoring adverse risks remains important. This study aimed to estimate the neuropsychiatric and cardiovascular risks associated with varenicline and NRT as used in routine UK care.DESIGN: Case crossover study.SETTING: UK based electronic primary care records in the Clinical Practice Research Datalink from 2006 to 2015 linked to hospital and mortality datasets.PARTICIPANTS: Adult smokers (n=?) observed in periods when exposed and not exposed to either varenicline or NRT.MEASUREMENTS: Main outcomes included suicide, self-harm, myocardial infarction (MI), all-cause death and cause-specific death (MI, chronic obstructive pulmonary disease (COPD)). In primary analyses, conditional logistic regression was used to compare the chance of varenicline or NRT exposure in the risk period (90 days prior to the event) with the chance of exposure in an earlier single reference period (91-180 days prior to the event) or multiple 90-day reference periods to increase statistical power.FINDINGS: In the primary analyses, findings were inconclusive for the associations between varenicline and the main outcomes using a single reference period, whilst NRT was associated with MI (Odds ratio (OR) 1.40, 95% Confidence interval (CI) 1.18-1.67). Using multiple reference periods, varenicline was associated with an increased risk of self-harm (OR 1.32, 95% CI 1.12-1.56) and suicide (OR 3.56, 95% CI 1.32-9.60) but a reduction in all-cause death (OR 0.75, 95% CI 0.61-0.93). NRT was associated with MI (OR 1.54, 95% CI 1.36-1.74), self-harm (OR 1.30, 95% CI 1.18-1.44), and deaths from MI (OR 1.53, 95% CI 1.11-2.10), COPD (OR 1.33, 95% CI 1.14-1.56) and all causes (OR 1.28, 95% CI 1.18-1.40) when using multiple reference periods.CONCLUSIONS: There appear to be positive associations between 1) nicotine replacement therapy (NRT) and myocardial infarction, death, and risk of self-harm and 2) varenicline and increased risk of self-harm and suicide, as well as a negative association between varenicline and all-cause death. The associations may not be causal. They may reflect health changes at the time of smoking cessation (NRT is prescribed for people with cardiac problems) or be associated with quit attempts (exposure to both medicines was associated with self-harm).</p